1. Field of the Invention
The present invention relates to a display device, and more particularly to a liquid crystal display device, and fabricating and driving method thereof.
2. Description of the Related Art
A liquid crystal display (hereinafter referred to as “LCD”) device controls light transmittance of liquid crystal cells in accordance with a video signal to display a picture. The LCD device utilizes an active matrix of cells in which a switching device is used in each cell. The LCD device can be configured for use in several different types of display devices, such as computer monitor, television monitor and cellular phone display. A thin film transistor (hereinafter referred to as “TFT”) is mainly used as the switching device in the active matrix of the LCD device.
FIG. 1 represents a driving device of an LCD device of the related art. Referring to FIG. 1, the driving device of the LCD device of the related art includes a liquid crystal panel 152 where m×n number of liquid crystal cells Clc are arranged in an active matrix having m number of data lines D1 to DM crossing n number of gate lines G1 to Gn, and a TFT formed adjacent to each of the crossings; a data driver 64 for supplying a data signal to the data lines D1 to Dm of the liquid crystal panel 152; a gate driver 66 for supplying a scan signal to the gate lines G1 to Gn; a gamma voltage supplier 68 for supplying a gamma voltage to the data driver 64; a timing controller 60 for controlling the data driver 64 and the gate driver 66 using a synchronization signal supplied from a system 70; a DC/DC converter 74 for generating voltages supplied to the liquid crystal panel 52 from a voltage supplied by a power supplier 62; and an inverter 76 for driving a backlight 78. The system 70 supplies a vertical/horizontal synchronization signal Vsync, Hsync, a clock signal DCLK, a data enable signal DE and data RGB to the timing controller.
The liquid crystal panel 52 includes a plurality of liquid crystal cells Clc that are arranged in a matrix shape defined by the crossing of data lines D1 to Dm and gate lines G1 to Gn. A TFT is respectively formed in each of the liquid crystal cells Clc to switch the data signal from the data lines D1 to Dm in response to the scan signal supplied from the gate line G. Further, a storage capacitor Cst is formed in each of the liquid crystal cells Clc. The storage capacitor Cst is formed between the pre-stage gate line and the pixel electrode of the liquid crystal cell Clc, or formed between a common electrode line and the pixel electrode of the liquid crystal cell Clc, thereby fixedly sustaining the voltage of the liquid crystal cell Clc.
The gamma voltage supplier 68 supplies a plurality of gamma voltages to the data driver 64. The data driver 64 converts the digital video data RGB to an analog gamma voltage (data signal) corresponding to the gray level value in response to the control signal CS from the timing controller, and supplies the analog gamma voltage to the data lines D1 to Dm. The gate driver 66 sequentially supplies a scan pulse to the gate lines G1 to Gn in response to the control signal CS from the timing controller 60, thereby selecting a horizontal line of the liquid crystal panel 52 to which the data signal is supplied.
The timing controller 60 generates the control signal CS for controlling the gate driver 66 and the data driver 64 by use of the vertical/horizontal synchronization signal Vsync, Hsync and the clock signal DCLK which are inputted from the system 70. Herein, the control signal CS for controlling the gate driver 66 includes gate start pulse GSP, gate shift clock GSC, and gate output signal GOE. And the control signal CS for controlling the data driver 64 includes source start pulse GSP, source shift clock SSC, source output signal SOE, and polarity signal POL. The timing controller 60 also re-arranges the data RGB supplied from the system 70 for supply to the data driver 64.
The DC/DC converter 74 boosts or reduces the voltage of 3.3V input from the power supplier 62 and generates a voltage to be supplied to the liquid crystal panel 52. The DC/DC converter 72 generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL, and a common voltage Vcom.
The inverter 76 drives the backlight 78 by use of the drive voltage Vinv supplied from any one of the power supplier 62 or the system 70. The backlight 78 is controlled by the inverter 76 to generate light to supply to the liquid crystal panel 52.
In the liquid crystal display 52 of the liquid crystal display device of the related art, constant light is always supplied from the backlight 78 regardless of the amount of available light in the external environment. Thus, the backlight may provide insufficient lighting to the liquid crystal panel in a bright light environment or waste power in a low light environment. To solve these problems, a technique is proposed in that the external light is sensed by use of a photo-sensor, such as a photodiode, and the brightness of the backlight 18 is adjusted by a user's manipulation. However, the photo-sensor is not located within the liquid crystal panel 52 such that its reliability is decreased. Further, there is cost increase if the photo-sensor is separately added to the LCD device.